A fact table stores some KIND of measurements. Usually these measurements are stored (or CAPTURED) against a SPECIFIC time and these measurements vary with respect to time. Now it might so HAPPEN that the business might not able to capture all of its measures always for every point in time. Then those unavailable measurements can be kept empty (Null) or can be filled up with the LAST available measurements. The first case is the example of incident fact and the second one is the example of snapshot fact.

A fact table stores some kind of measurements. Usually these measurements are stored (or captured) against a specific time and these measurements vary with respect to time. Now it might so happen that the business might not able to capture all of its measures always for every point in time. Then those unavailable measurements can be kept empty (Null) or can be filled up with the last available measurements. The first case is the example of incident fact and the second one is the example of snapshot fact.